Heartworm in Cats: What You Need to Know to Protect Your Cat

Thinking about your cat having any sort of illness is a terrifying thought, but heartworms are one of the last things you want your cat to suffer from. Considering how quickly a heartworm can affect and potentially lead to death in your cat. Which is why it’s important to learn about the diagnostic tests that can be performed as well as preventative measures that can be taken.

Heartworm disease in cats is just as scary as heartworms in dogs, but there are some differences in the diseases between the two different species of animal. 

What are Heartworms?

Heartworms are a type of parasitic roundworm called Dirofilarial immitis that are transmitted from one host to the next through mosquito bites. These worms live in the heart, lungs, and other blood vessels of the animal that is hosting them and can lead to severe lung disease, heart failure, and even damage to other organs in their body.

Heartworm disease is completely different when looking at a dog compared to a cat. Canines are considered to be natural hosts to heartworms, meaning the worms will live within the dog for a fair amount of time until they have matured. Maturation of heartworms in dogs means that the parasite has grown to their full size and is able to mate and produce offspring within the dog.

In cats however, the worms do not live their full lifespan generally. This is because cats are not a natural host for heartworms. Even though the heartworms don’t reach adulthood in cats, they can still cause some serious damage within the body of a cat. Therefore, it’s important to get your dogs or cats screened for heartworms as well as given the appropriate preventative treatments. 

Heartworm Symptoms in Cats?

The symptoms of heartworms in cats can be either incredibly subtle or very noticeable and even severe. Some of the more apparent symptoms of heartworms in cats include coughing spells, attacks that could be mistaken for asthma, lack of appetite, and subsequent weight loss. 

Other symptoms that can occur in cats who have heartworms include fainting spells, accumulation of fluid in the abdomen, trouble walking and getting around, and even sometimes seizures. Unfortunately, sometimes the only symptom a cat will show of being affected by heartworms is passing out or sudden death.

How Do They Test a Cat for Heartworms?

The diagnosis of heartworms in cats is minimally invasive. All that would need to occur to make a diagnosis is a physical exam by a veterinarian, some blood tests, and an x-ray. An ultrasound is also a possible test that a vet may run to check your cat for the presence of heartworms

What Happens if My Cat Gets Heartworms?

There are unfortunately no FDA approved drugs or treatments for cats that are afflicted with heartworms.  This is why prevention is so important. Taking your pet to be screened for heartworms at a young age is a good place to start. From there, it's important to follow the steps that your vet instructs you to take to keep your cat safe. This also includes ensuring that your cat's vaccinations are up to date.

There is the rare instance that a cat can experience “spontaneous clearing” of heartworms. Sadly, there will still be damage that the heartworms will have caused. If heartworms are present in a cat’s lungs, it is recommended that they get an x-ray every 6-12 months to monitor the worms. Doses of prednisone can help with symptom management. 

How Can I Prevent Heartworms in my Cat?

There may not be workable treatments available for cats who have contracted heartworm disease, but there are steps you can take to prevent your cat from getting them in the first place. Taking your cat to the vet regularly for screening is step one.

Your vet will be able to recommend different types of prevention methods that you use for your cat. There are monthly pills they can take, or spot on treatments that go on the back of your cats’ neck monthly.

These preventative treatments help to keep cats from developing heartworms if they get an infected mosquito bite. 


You love your cat very much and would never want to receive the news that they have contracted heartworms from a mosquito bite.

Heartworm disease in cats can be incredibly severe or sudden but is thankfully preventable when the correct steps are taken. The symptoms can be very subtle or undetectable all together, which is why prevention is so important. 

Is heartworm in cats fatal?

Yes, heartworms in cats are certainly fatal. This is because when a heart worm dies it releases toxic substances into the cat’s blood stream. These substances can go to the cats’ lungs, leading to potential respiratory issues or in the worst-case scenario, death. This is why it’s so important to have you cat screened and treated for heartworms.

How long do heartworms live in cats?

Heartworms in cats have shorter lifespan than that of heartworms in dogs. On average, heartworms are known to live 2 to 4 years in cats. Meaning that they do not typically grow as long as they might in dogs, nor do all of them mature into adult heartworms.

Can you get rid of heartworms in cats?

Unfortunately, there is no FDA approved treatment on the market for heartworms in cats as of right now. Therefore, prevention is key. In the case that your cat does develop heartworms, if they can be seen via ultrasound there is a chance that they could be surgically removed from your cat. Otherwise, symptom management is the course of treatment for a cat that is infected with heartworms.

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Written by Leo Roux

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